Is it true that high temperature baking can change the hardness of silica gel?


2020/12/18 10:07:04



What is the hardness of silica gel? In the silicone industry, the unit to measure the softness of silicone rubber is called silicone rubber hardness, and the unit of silicone rubber hardness is Shore A hardness and Shore C hardness. Generally, during the curing process of liquid silica gel, the hardness of silica gel will rise slowly until it reaches its peak. So how is the hardness of silica gel measured? The hardness of liquid silicone mold is measured in Shore A, ranging from 0 to 50 degrees, the softest hardness is Shore A 0 degrees, and the hardest hardness can reach Shore A 50 degrees, with a unit every five degrees in the middle. Then some users have questions, why is the hardness of the silicone we bought last time different from that we bought this time, with a deviation of 2 degrees? This is because silica gel belongs to chemical raw materials, and there will be errors in the production process of chemical raw materials, but such errors are within a reasonable range. Within this reasonable hardness error range, it will not affect the operation and use of silica gel.



But there is a saying on the Internet that baking at high temperature can change the hardness of silica gel, which is not completely correct. When the curing agent is added to the liquid silica gel in proportion in the liquid state, the silica gel will gradually thicken and the hardness of the silica gel will gradually increase after being baked at high temperature. Addition liquid silica gel is usually baked at 100-200℃ and cured in about 10-15 minutes. Condensed silica gel will not cure quickly in a short time after being baked at high temperature. However, after the silica gel has been cured, baking at high temperature will accelerate the aging of silica gel, which will make the hardness of silica gel rise falsely, and accelerate the brittleness, tear strength, tensile strength and elongation. This is the aging process of silica gel after continuous high temperature.


How to change the hardness of silica gel? When the user feels that the hardness of silica gel is too hard, the hardness of silica gel can be adjusted by adding silicone oil, and the hardness decreases by one degree for every 2% dimethyl silicone oil. If the hardness of silica gel is soft, how to adjust it? You can choose to add hydrogen-containing silicone oil in proportion.






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